Android: Fix ANR when boot fails

android/app/src/cpp/android_host_interface.cpp

@@ -194,7 +194,9 @@ void AndroidHostInterface::PauseEmulationThread(bool paused)
 
 void AndroidHostInterface::StopEmulationThread()
 {
-  Assert(IsEmulationThreadRunning());
+  if (!IsEmulationThreadRunning())
+      return;
+
   Log_InfoPrint("Stopping emulation thread...");
   {
     std::unique_lock<std::mutex> lock(m_mutex);

android/app/src/main/java/com/github/stenzek/duckstation/EmulationActivity.java

@@ -100,6 +100,7 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
 
     public void onEmulationStopped() {
         runOnUiThread(() -> {
+            AndroidHostInterface.getInstance().stopEmulationThread();
             if (!mWasDestroyed)
                 finish();
         });